Early life conditions and long-term sickness absence during adulthood - A longitudinal study of 9000 siblings in Sweden

This study examines the influence of health conditions experienced during the individual's first year of life on the incidence of sickness absence during adulthood. Using a sample of approximately 9000 biological siblings from 17 countries of origin and living in Sweden during the time period 1981-1991, sibling fixed effect models are estimated. This approach is combined with the use of an exogenous measurement of early life conditions, operationalized as the infant mortality rate. The link between early life conditions and later life outcomes is examined both with and without intermediary characteristics observed during the individual's childhood and adulthood, aiming for a better understanding regarding to what extent the effect of exposure to an early life insult can be mediated. The results suggest that exposure to worse health conditions during the first year of life is associated with an elevated risk of experiencing sickness absence during adulthood. An increase in infant mortality rate by ten per thousand is associated with a four percentage point higher probability of experiencing sickness absence. Despite the importance of adulthood socioeconomic status on sickness absence propensity, these factors do not mediate the influence from the health conditions experienced during the first year of life, suggesting that the association from early life conditions on sickness absence in adulthood operates as a direct mechanism. The link between early life conditions and sickness absence is only present for children to parents with primary schooling and not for individuals with more educated parents. These findings suggest that families with more abundant resources have the ability to protect their child from exposure to adverse health conditions during early life, or to cancel out the influence from an early life insult. © 2014 Elsevier Ltd.